Single-handle mixing valves have become commonplace. However, many compromises have been built into mixing valves to accommodate high flow-volumes and easy temperature control. Also, while limiting devices have been used, they are generally complicated mechanisms that cannot be easily repaired or replaced.
Since water ignition systems control many home water heaters, water is quickly heated to the selected temperature when the water outlet is opened. A normal home water heater can heat water to more than 150.degree. F., whereas optimum water temperature for washing and bathing is maintained between 95.degree. F. and 104.degree. F. Scalding occurs at about 115.degree. F. Accordingly, it is practical to limit the maximum water temperature. Also, with the changes of seasons and changes in settings of the water heater, the water temperature being dispensed varies.
Anti-scald configurations are known for shower handles where a single handle controls the full range of water temperatures. The handle generally moves through a wide range of motion so that the person taking the shower can make minor adjustments without risking being exposed to severe temperature changes. By limiting the range of motion of these handles, scalding temperatures are avoided. Similarly, in single-handle modular cartridge valves, an insert interposed between the operating stem and the temperature control knob orientates the knob with respect to the valve housing.
The single-handle mixing valve generally has a control stem extending out from the valve housing and connectable to a control stem to control the position of the valve. The range of motion of flow-volume and water temperature is defined by the shape of the opening in the guide template. The internal position of the volume and temperature limiting devices renders them difficult to change. In addition, repair or replacement of the limit structures requires that the main water line be shut off from the valve.
The primary problem still remaining is to adjust the maximum water output and to suitably limit the temperature of the mixed water when the valve is fully opened. Such a possibility appears desirable for a more efficient use of mixing valves by preventing an unnecessary waste of water and, in particular, of hot water in order to prevent scalding and to achieve a substantial saving of energy.
What is needed is a single-handle mixing valve having a valve housing that prevents excessively high water temperatures and flow-volumes; that includes means for retaining interchangeable cams as part of the valve housing, each cam either having or not having maximum flow-volume and temperature stops enabling the ready replacement of the cam without the need to disassemble the valve housing, that is simple in structure, durable in use, and economical to make.
What is needed is an easily assembled limiting device for use with a single-handle mixing valve which provides full adjustment of the flow-volume and temperature in a cartridge-type configuration that can be readily adjusted for varying maximum flow-volume and/or maximum temperature; that can be applied to the exterior of the valve housing; that has valve mechanisms housed in a cartridge that can be easily replaced when necessary; and that is independent of the guide mechanism to enable easy replacement of limiting elements for changing the maximum flow-volume and temperature profile of the mixing valve without disassembly of the valve housing.
What is needed is a limiting device for an improved single-lever flow-control valve which has a long service life and that can be varied in the field either during installation or servicing without any special tools simply be either adding an insert to a guide template or by replacing an insert with another insert having a different controlling edge.